Refrigeration apparatus

Abstract

A refrigeration apparatus uses a refrigerant that operates in a supercritical range. The refrigeration apparatus includes a compression mechanism, a heat source-side heat exchanger, an expansion mechanism, a usage-side heat exchanger, a switching mechanism, an intercooler which functions as a cooler of refrigerant discharged from a first-stage compression element of the compression mechanism and drawn into a second-stage compression element of the compression mechanism, and an intercooler bypass tube. The switching mechanism is configured to switch between cooling and heating operation states in which refrigerant is circulated differently. When a defrosting operation for defrosting the heat source-side heat exchanger is performed, refrigerant flows to the heat source-side heat exchanger and the intercooler. After defrosting of the intercooler is detected as being complete, the intercooler bypass tube is used to ensure that the refrigerant does not flow to the intercooler.

Description

TECHNICAL FIELD[0001]The present invention relates to a refrigeration apparatus, and particularly relates to a refrigeration apparatus which has a refrigerant circuit configured to be capable of switching between a cooling operation and a heating operation and which performs a multistage compression refrigeration cycle by using a refrigerant that operates in a supercritical range.BACKGROUND ART[0002]As one conventional example of a refrigeration apparatus which has a refrigerant circuit configured to be capable of switching between a cooling operation and a heating operation and which performs a multistage compression refrigeration cycle by using a refrigerant that operates in a supercritical range, Patent Document 1 discloses an air-conditioning apparatus which has a refrigerant circuit configured to be capable of switching between an air-cooling operation and an air-warming operation and which performs a two-stage compression refrigeration cycle by using carbon dioxide as a refrig...

AI Technical Summary

Benefits of technology

[0007]As a countermeasure to this problem, in this refrigeration apparatus, the intercooler which functions as a cooler of the refrigerant discharged from the first-stage compression element and drawn into the second-stage compression element is provided to the intermediate refrigerant tube for drawing refrigerant discharged from the first-stage compression element into the second-stage compression element, the intercooler bypass tube is connected to the intermediate refrigerant tube so as to bypass the intercooler, the intercooler bypass tube is used to ensure that the intercooler functions as a cooler when the switching mechanism corresponding to the aforementioned four-way switching valve is set to a cooling operation state corresponding to the air-cooling operation, and also that the intercooler does not function as a cooler when the switching mechanism is set to a heating operation state corresponding to the air-warming operation. This minimizes the temperature of the refrigerant discharged from the compression mechanism corresponding to the aforementioned compressor during the cooling operation, suppresses heat radiation from the intercooler to the exterior during the heating operation, and prevents loss of operating efficiency.

[0010]In view of this, in this refrigeration apparatus, after defrosting of the intercooler is detected as being complete, the intercooler bypass tube is used to ensure that refrigerant does not flow to the intercooler, whereby heat is not radiated from the intercooler to the exterior, the temperature decrease in the refrigerant drawn into the second-stage compression element is minimized, and as a result, the temperature decrease in the refrigerant discharged from the compression mechanism is minimized, and the loss of defrosting capacity of the heat source-side heat exchanger is minimized.

[0011]When the defrosting operation is performed in this refrigeration apparatus, it is thereby possible to defrost the intercooler as well and to minimize the loss of defrosting capacity caused by heat radiation from the intercooler to the exterior, which can also contribute to reducing the defrosting time.

Problems solved by technology

As a result, since the refrigerant discharged from the second-stage compression element of the compressor has a high temperature, there is a large difference in temperature between the refrigerant and the water or air as a cooling source in the outdoor heat exchanger functioning as a refrigerant cooler, and the outdoor heat exchanger has much heat radiation loss, which poses a problem in making it difficult to achieve a high operating efficiency.

With this refrigeration apparatus, there is a danger of frost deposits forming in the intercooler in cases in which a heat exchanger whose heat source is air is used as the intercooler and the intercooler is integrated with a heat source-side heat exchanger whose heat source is air.

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